ABSTRACT
To ensure the safe demolition construction of a 63 m span concrete box girder in an upper closed span frame channel, steel tube columns, and bowl-buckle supports are installed under the box girder to be demolished as temporary load-bearing structures to realize the transformation of box girder supporting structure from existing capping beams to temporary load-bearing structures. Based on the numerical calculation and analysis of different cutting steps, it is determined that when the rigid support is transformed into the flexible support, the way of cutting the middle first is safer for the lower bowl-buckle support to bear the force; the steel tube column structure is erected above the load-bearing wall of the lower closed frame passage, and the gantry crane is erected on the steel tube column structure. Considering the load-bearing capacity of the gantry crane and the steel tube column structure, the concrete mass box girder is divided by a rope saw, and blocks can lift the long-span concrete box girder without a crane. Therefore, reasonable design of temporary support, cutting sequence, and lifting and removing equipment can realize the safe demolition of long-span concrete box girders without affecting the normal passage of closed frame channel, which has reference significance for the demolition construction of similar reinforced concrete structures.
